Comparison of serum creatinine, point-of-care symmetric dimethylarginine and renal imaging with glomerular filtration rate measured by renal scintigraphy in healthy and early chronic kidney diseased cats.

The aim of this study was to evaluate routinely used tests to diagnose cats in early stages of chronic kidney disease (CKD) and to describe a model for evaluating these variables simultaneously. Apparently healthy cats were screened using serum creatinine (sCr), point-of-care symmetric dimethylarginine (POC SDMA), urinalysis, urine protein/creatinine ratio (UPC) and imaging evaluation. Those parameters were compared to glomerular filtration rate (GFR) assessed by renal scintigraphy. Forty-four cats were included and consisted of 14 (31.8%) healthy cats (absence of abnormalities in renal morphology and sCr less than 1.6 mg/dL), 20 (45.5%) cats classified as CKD I (presence of abnormalities in renal morphology and sCr less than 1.6 mg/dL) and ten (22.7%) as CKD II (sCr equal to or greater than 1.6 mg/dL, with or without abnormalities in renal morphology). A large number (40.9%) of apparently healthy cats presented reduction in GFR, which included half of CKD I patients. Point-of-care SDMA was not a good predictor for decreased GFR, nor was it correlated with the variables GFR and sCr. Glomerular filtration rate was significantly lower in CKD I and II groups in comparison with healthy cats, but there was no significant difference between the CKD I and II groups. Multivariate logistic regression model identified three variables that affected the odds of a cat having decreased GFR (< 2.5 mL/min/kg): sCr (OR = 18.3; p = 0.019; CI = 1.6-207.2), and the ultrasonographic findings 'reduced corticomedullary definition' (OR = 19.9; p = 0.022; CI = 1.6-254.0) and 'irregular contour' (OR = 65.6; p = 0.003; CI = 4.2-1038.2). Renal ultrasonography evaluation should always be considered for screening early CKD in apparently healthy cats.